docs: def _make_sampling_sequence(n):
      # type: (int) -> List[int]
      """
      Return a list containing the proposed call event sampling sequence.
  
      Return events are paired with call events and not counted separately.
  
      This is 0, 1, 2, ..., 4 plus 50, 100, 150, 200, etc.
  
      The total list size is n.
      """
      seq = list(range(5))
      i = 50
      while len(seq) < n:
          seq.append(i)
          i += 50
      return seq